An abandoned well located 400 m from a municipal water well was used by miss Magda of the Devil's Grail Enterprises, Inc. as an illegal hazardous waste disposal site. The aquifer is confined, has thickness 10 m, transmissivity 10-2 m2/s, and porosity 0.2. The municipal well is 1.0 m in diameter and has been pumping steadily at 0.1 m3/s for 20 days. Measured drawdown in the abandoned well is 6.2 m.
- Map the drawdown distribution around the pumping well and determine the travel time from the abandoned well to the pumping well.
- A first trace of the contaminant has just been detected in a monitoring well 50 m from the municipal well. It has caused a panic among the people responsible for the quality of water. They hired an outside consultant. The consultant recommended that the pumping process be reversed. The municipal well should become an injection well. After some time, the contaminant would flow back to the abandoned well, where it would be neutralized. Will the plan work? Why or why not? Discuss qualitatively, but in detail.
USE MAGNET to aid the solution of this problem. Represent the contamination source at the well as a pulse release of "particles", taking into account dispersion, use particle tracking with dispersion or random walk.
MAGNET/Modeling Hints:
- Use 'Synthetic Mode' to set up your flow model ( 'Other Tools' > 'Utilities' > 'Go to Synthetic Case Area')
- Use the ‘Distance Display’ capabilities when editing geometric features and/or the ‘Ruler’ tool to properly represent distances between model features.